JPS6240316B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention uses iron/lead tungstate [Pe _2/3 W _11/3 ] O ₃ ] iron/lead niobate [Pb
(Fe _1/2 Nb _1/2 ) O ₃ ]-based ceramic composition. It is well known that as a conventional high permittivity dielectric material, a material containing barium titanate [BaTiO ₃ ] as a main component has been widely put into practical use. However, the sintering temperature for materials whose main component is _BaTiO3 is usually
The high temperature is 1300°C to 1400°C, and especially in the case of multilayer capacitors, the drawback is that an expensive noble metal such as platinum or palladium must be used as the main component for the internal electrode suitable for this sintering temperature. had. Therefore, in order to make it possible to use inexpensive internal electrodes mainly composed of silver or the like, there has been a strong demand for a dielectric material that can be sintered at as low a sintering temperature as possible, particularly at a temperature of 1000° C. or lower. An object of the present invention is to provide a composition that can be sintered at a temperature of 1000°C or lower, has a significantly high dielectric constant, low dielectric loss, and high specific resistance. The inventors have already discovered that Pb can be sintered at temperatures below 1000℃.
A binary high permittivity ceramic composition consisting of (Fe _2/3 W _1/3 ) O ₃ and Pb (Fe _1/2 Nb _1/2 ) O ₃ was proposed (Japanese Patent Application Laid-Open No. 1987-87700). This composition has excellent dielectric properties and is about to be put into practical use as a magnetic capacitor. However, the dielectric loss and resistivity were somewhat unsatisfactory, and the application had to be limited to a narrow range. The present invention uses this two-component composition as Pb
(Fe _2/3 W _1/3 ) x (Fe _1/2 Nb _1/2 ) _1-x O ₃ When the mixing ratio By containing 0.02 to 1 atomic percent of at least one kind of rare earth metal element as a component, it maintains a high dielectric constant, reduces dielectric loss, and increases specific resistance, making it easy to mass produce, inexpensive, and excellent. The present invention provides a high dielectric constant ceramic composition. The present invention will be explained in detail below using examples. Examples Starting materials include lead oxide (PbO), iron oxide (Fe ₂ O ₃ ), tungsten oxide (WO ₃ ), niobium oxide (Nb ₂ O ₅ ), lanthanum oxide (La ₂ O ₃ ), and cerium oxide (CeO _{2 ).} ), neodymium oxide (Nd ₂ O ₃ ), samarium oxide (Sm ₂ O ₃ ), and oxide (Gd ₂ O ₃ ) are weighed to a predetermined mixing ratio.Next, after wet mixing in a Pall mill, 750 After pre-firing at ℃~850℃ and pulverizing this powder, it is crushed into a powder with a diameter of ^approx .
After pressure molding into a cylinder of 16mm and approximately 10mm thick, 880
Sintered at ℃~980℃. The obtained sintered body is about 0.5mm
After cutting into disks, silver electrodes were baked. The relationship between the blending ratio and various properties of the magnetic composition thus obtained is shown in the table.

【table】

[Table] Here, the dielectric constant and dielectric loss are at a frequency of 1KHz,
Measured at a temperature of 20°C. The specific resistance was measured at a temperature of 20°C by applying 100V DC. As is clear from the table, by containing at least one rare earth metal element as a subcomponent, it is possible to maintain a high dielectric constant, reduce dielectric loss, and significantly increase specific resistance, making it practical. It can be seen that an excellent high dielectric constant ceramic composition rich in porcelain compositions can be obtained. Since the sintering temperature is low, below 1000°C, it not only significantly improves the durability of furnace materials and reduces manufacturing costs due to reduced electricity costs, but it is especially effective for large-capacity multilayer capacitors. The present invention provides a material that is highly mass-producible and can reduce the cost of internal electrodes. In addition, a composition in which the main component blending ratio x is less than 0.2 or more than 0.5 has a low dielectric constant at room temperature because the Curie point is largely shifted to a higher temperature side or a lower temperature side than room temperature. Further, if the content of one or more metal elements among the rare earth metal elements as subcomponents is less than 0.02 atomic %, the effect of improving dielectric loss and resistivity is small, and if it exceeds 1 atomic %, dielectric loss becomes large. Although oxides were mainly used as raw materials in the above embodiments, it goes without saying that the same effect can be obtained by using raw materials that easily become oxides by sintering, such as carbonates.

Claims (1)

[Claims] 1. Iron/lead tungstate [Pb
(Fe _2/3 W _11/3 )O ₃ ] and iron/lead niobate [Pb
(Fe _1/2 Nb _1/2 )O ₃ ]
_{( Fe 2/3 W 1/3 )} At least one rare earth metal element is added as a subcomponent to the main component composition.
A high dielectric constant ceramic composition characterized by containing 0.02 atomic % or more and 1 atomic % or less.